Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 54: Electron Theory of Magnetism and Micromagnetic Simulations
MA 54.2: Vortrag
Freitag, 11. März 2016, 10:15–10:30, H34
The Gilbert damping in random ferromagnetic alloys from the LMTO method — •Ilja Turek1, Josef Kudrnovsky2, and Vaclav Drchal2 — 1Institute of Physics of Materials, Acad. Sci. Czech Rep., Brno, Czech Republic — 2Institute of Physics, Acad. Sci. Czech Rep., Prague, Czech Republic
We present an ab initio theory of the Gilbert damping tensor for spin-polarized random alloys within the relativistic tight-binding LMTO method and the coherent potential approximation (CPA) [1]. The formulation employs the atomic-sphere approximation which leads to effective nonlocal torque operators entering the LMTO torque-correlation formula. In contrast to traditional local torque operators [2, 3], the nonlocal torques are nonrandom and spin-independent; the CPA-vertex corrections are indispensable for an exact equivalence of both torques. The developed theory has been applied to random ferromagnetic alloys of 3d elements (Fe, Co, Ni), to pure iron with a model atomic-level disorder (simulating the effect of a finite temperature), and to stoichiometric FePt alloys with a varying degree of the L10 atomic long-range order. [1] I. Turek et al., arXiv: 1510.03571 (2015). [2] H. Ebert et el., Phys. Rev. Lett. 107, 066603 (2011). [3] A. Sakuma, J. Phys. Soc. Japan 81, 084701 (2012).